Large-scale implementation of Cognitive Processing Therapy (CPT), an evidence based treatment for Post- traumatic Stress Disorder, can have a tremendous impact on mental and physical health, healthcare utilization, and quality of life. Several large mental health systems have invested heavily in programs to train their clinicians in CPT, but relatively little attention has been devoted to the monitoring or promotion of fidelity after training is complete. Identifying strategies to monitor fidelity is critical to ensuring consmer access to high quality, evidence-based treatments (EBTs). Emerging evidence suggest that when CPT and other cognitive behavioral therapies (CBT) are delivered with low levels of fidelity, clinical outcomes are negatively impacted. Yet few clinicians deliver EBTs with fidelity n everyday practice, and the likelihood of drift increases after training is complete. Implementation models therefore highlight the importance of ongoing fidelity monitoring and support. The lack of a scalable, effective, and efficient method of monitoring fidelity is a key barrier to efforts to monitor and enhance fidelity for CPT and other CBTs. Observation and expert ratings are time- and resource-intensive and unlikely to be feasible or affordable in large systems. Self-report fidelity assessments increase clinician and consumer burden and there is evidence that they may not accurately reflect in-session behavior. To date, monitoring strategies that do not involve observation, client/caregiver reports, or clinician self-reports have not been tested. To address this critical implementation challenge, we propose to refine and evaluate a method of monitoring fidelity that utilizes clinical progress notes and CPT worksheets that are routinely completed in session. Because the worksheets were developed to guide the implementation of core CPT elements, they may be used to corroborate information from progress notes and to elucidate the clinician's ability to convey key skills and concepts in session. Consultation with stakeholders in large mental health systems suggests that because this method minimizes the time required to collect and assess fidelity, it is feasible and preferable to observation and self-reports. Preliminary data indicates that this strategy is promising. This research will be conducted by a team of investigators with expertise in CPT and CBT, training, implementation, psychotherapy process and outcome research, psychometric methodologies, and longitudinal data analysis, with input from community stakeholders. Because the core elements of CPT and its worksheets are based on and common to other CBTs, this research has broad implications for monitoring fidelity to CBTs in a variety of mental health and healthcare systems and settings. This research will set the stage for subsequent research to evaluate the measure to monitor and support fidelity in these settings. The resulting products have the potential to significantly improve effots to monitor and ensure ongoing high quality implementation of CPT in community and VA settings.